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CASE STUDIES OF HIGH STRENGTH WASTEWATER...These cleaning products, however, can often stress septic...
Transcript of CASE STUDIES OF HIGH STRENGTH WASTEWATER...These cleaning products, however, can often stress septic...
CASE STUDIES OF HIGH STRENGTH WASTEWATER
Sara Heger
Presentation Overview
◦Key design parameters ◦Case Studies◦ Adult care facilities◦ Rest areas
◦General design solutions
KEY DESIGN PARAMETERS
Commercial Wastewater◦Strength◦Usually greater than residential◦Operation based◦ Food preparation◦ Restrooms◦ Laundry
◦Maybe high strength◦Maybe hard to treat
Commercial ChallengesHigh Strength
◦ Food service◦ Food preperation◦Alcohol◦Dairy◦ Sugar
Hard to Treat◦Cleaning chemicals◦ Sanitizers◦ Anti-bacterial◦ Quats
◦ Emulsifiers◦Greases◦Dump stations◦Medicines
High Strength Waste
Caused by:◦ High inputs of BOD, TSS and Oil & Grease◦ Nitrogen
◦ Lack of dilution from low waste strength inputs (shower, laundry, etc..)◦ Chemical upset of the septic tank ◦ Operational/maintenance issues (lack of tank
pumping or missing baffles)
High Strength Waste
◦Reminder that the mass of the solids is the issue ◦We use concentration because we assume normal volume of sewage will be produced
High Strength Wastewater
1) Influent having BOD5 > 300 mg/L, and/or TSS > 200 mg/L, and/or fats, oils, and grease (FOG) > 50 mg/L entering a
pretreatment component 2) Effluent from a septic tank or other pretreatment
component that has: BOD5 > 170 mg/L, and/or TSS > 60 mg/L, and/or (FOG) > 25 mg/L and is applied to an infiltrative
surface.
High Strength for Nitrogen
◦No national definition◦Typically values greater then 60 mg/l are considered high strength
Biochemical Oxygen Demand (BOD)◦ Amount of oxygen consumed by microbes
during decomposition of organic matter ◦ Indicates overall organic strength of wastewater ◦ High BOD5 means high levels of organics◦ CBOD – Carbonaceous Biochemical Oxygen Demand◦ NBOD – Nitrogenous Biochemical Oxygen Demand (NH4
to NO3)◦ UBOD- Ultimate Biochemical Oxygen Demand (Oxidize,
Cell mass, Endogenous respiration)
Total Suspended Solids◦ Total Suspended Solids (TSS)
◦ Solids that don’t pass through filter ◦ Mixture of organic and inorganic
particles
◦ Organic vs inorganic components◦ Organic can be digestible◦ Inorganic cannot be digested
◦ Sources◦ Organic matter (garbage disposal)◦ Toilet paper◦ Lint◦ Dirt◦ Other solids
◦ Plastics◦ Feminine hygiene products
Fats, Oils, and Grease (FOG)
◦Degradable◦ Animal or vegetable-based FOG◦ Kitchens
◦Non-degradable◦ Petroleum-based FOG◦ Industry/automotive
repair◦ Bath oils, moisturizing
cream, tanning oils
A degreaser (emulsifier) will move all FOG components through a system
CASE STUDY: ADULT CARE
FACILITIES
Background
◦ 6 foster homes owned by same individual had reported various issues with their septic system operation and performance, including: ◦ surface discharge of wastewater and ◦ premature system failure
◦ The systems evaluated are conventional systems with septic tanks followed by in-ground soil treatment areas or mound systems◦ Septic tanks pumped annually
Example Faclity
Permanent Residents: 4Ave. Onsite Staff: 2Bedrooms: 4Bathrooms: 2
Methods
◦ Water Usage - staff who work in the facilities collected daily water meter readings for April–August 2013◦ Onsite Practices and Behaviors ◦ Staff provided feedback and assisted in completing a
survey◦ Provided inventories for each site listing all
pharmaceuticals and personal care products used in the facilities
Wastewater analysis◦ Samples obtained from outlet baffle of
septic tank or pump tank◦ Analyzed for:◦ Dissolved oxygen (DO), temperature and
pH◦ 5 day biochemical oxygen demand
(BOD5)◦ Total Kjeldahl nitrogen (TKN)◦ Total phosphorous (TP)◦ Total suspended soils (TSS)◦ Heterotrophic Plate Count (HPC) ◦ Surfactants - Methylene Blue Active
Substances – (MBAS) ◦ Contaminants of Emerging Concern (CEC)
Results – Water usage
Site
Flow, gpd
Mean Ave. Recorded
70% of Design
Design
A. Maple View 321 ± 13 525 750
B. Shady Lane 462 ± 6 420 600
C. Woods 326 ± 22 420 600
D. Jocelyn 630 ± 19 525 750
E. Upland 521 ± 6 840 600/1200
F. Meadows 491 ± 23 525 750
Results – water usage◦ Flow was higher than the ideal operating maximum (70%) at 2 sites (3 if
you take into account system that was expanded)◦ None of the sites exceeded the maximum design flow (on average)◦ Recommendations:
◦ Laundry◦ All sites use top-loading washers.◦ 1 to 12 loads in a single day◦ Convert to front-loading laundry machines ◦ Limit bleach usage
◦ Bathing, Washing, and Toilet Use◦ None of the homes had low-flow showerheads or toilets ◦ Convert to:
◦ low-flow showerheads (<2.0 gal per minute, gpm), ◦ sink faucets/fixtures (0.5–1.5 gpm), and ◦ toilets (<1.6 gal per flush)
Results - cleaning products
◦ Soap and detergents are often a significant part of maintaining a clean and hygienic home
◦ These cleaning products, however, can often stress septic systems when overused or disposed of improperly
◦ Personal Care Products - It would be prudent to reassess all cleaning products and personal care products
◦ Opting to use perfume- and dye-free alternatives will help cut down on unnecessary chemicals in wastewater
Results – soaps and detergents◦ Several antibacterial soap products and disinfectants are listed in
the site inventories◦ Some may be necessary (antibacterial denture cleaning tabs)
while others (hand soaps and dish detergents) are not* ◦ Replacing these products with non-antibacterial alternatives
should reduce stress to the microbial communities and will not affect hygiene
◦ Not all troublesome products are labeled as antibacterial. Mouthwash and toothpaste brands with triclosan as an active ingredient should be avoided
* Aiello, et al., 2007
Results – disposable wipes
◦ During several site visits, non-biodegradable products were observed in the pretreatment tanks at 3 sites
◦ Recommendation – Remove from facilities and remind staff as well as guests wipes, personal wet-cloths, and moist towelettes are not suitable for septic systems◦ These should be disposed of with solid waste
BOD5 data
SiteBOD5, mg/L
Mean Min. Max.
A. Maple View 143 ± 31.0 80.8 166
B. Shady Lane 129 ± 12.4 110 147
C. Woods 193 ± 34.2 159 235
D. Jocelyn 144 ± 41.5 93.4 195
E. Upland 182 ± 49.9 119 244
F. Meadows 132 ± 64.9 48.7 191G. Control Site 64 ± 30.7 38.6 114
TSS data and analysis
SiteTSS, mg/L
MeanAve.
Min. Max.
A. Maple View 46.5 ± 2.7 44.1 51.0
B. Shady Lane 38.9 ± 16.9 20.5 67.4
C. Woods 39.6 ± 8.7 28.2 54.5
D. Jocelyn 48.6 ± 10.5 36.7 65.3
E. Upland 51.1 ± 18.7 31.9 84.7
F. Meadows 24.7 ± 6.3 17.5 32.0
G. Control Site 40.3 ± 24.4 17.3 71.8
◦ All sites had TSS concentrations within the standard range*◦ Lint filters and
effluent screens recommended
* CIDWT Glossary, 2009
Methylene Blue Active Substances◦ MBAS are a group of
anionic surfactants accounting for as much as 63% of synthetic surfactant production worldwide*◦ Detergents, cleaners,
and soaps
◦ Surfactants do not typically pose a risk to groundwater, unless under saturated conditions, because of a strong tendency for soil sorption*
Hubbard, 2002, Reneau and Pettry, 1975, Weil-Shafran et al., 2006
MBABS & septic systemsConcentration
(mg/L MBAS)
Potential Effects
(Hernández Leal et al., 2011, and Weil-Shafran et al.,2006)
≥1.0
Risk of long-term accumulation ofsurfactants in soil, leading to decreasedhydraulic conductivity and increasedwater repellence
10Inhibition of hydrolysis, leading to greateraccumulation of solids in anaerobicsewage treatment systems
30 Direct degradation of soil structure anddecrease in hydraulic conductivity
MBAS results (1 sampling event)
SiteAnionic
Surfactants (MBAS), mg/L
A. Maple View 2.0
B. Shady Lane 0.76
C. Woods 3.8
D. Jocelyn 8.6
E. Upland 1.5
F. Meadows 3.4
G. Control Site 2.7
◦6/7 sites showed concentrations above the recommended 1.0 mg/L for soil treatment
Contaminants of Emerging Concern (CECs)◦ According to the EPA,
chemicals are being discovered in water and wastewater that previously had not been detected or are being detected at levels that may be significantly different than expected
◦ These are often referred to as “contaminants of emerging concern” (CECs), because the risk to human health and the environment associated with their presence, frequency of occurrence, or source may not be known
CECs◦ Pharmaceuticals and personal
care products (PPCPs)◦ Rare earth metals, radioactive
isotopes, and other unusual elements
◦ Pesticides, including insecticides, herbicides, and fungicides
◦ Hormones, steroids, and endocrine-disrupting compounds
◦ Genetic material, such as RNA or DNA (including antibiotic resistance genes)
◦ Various CECs were found at each of the sites
◦ This reflects the medical nature of the foster care homes and supports the notion that foster care homes have fundamentally different wastewater characteristics than average residential wastewater
◦ There are likely many other compounds present beyond the 26 included in this study
CEC units results
◦Nanograms/liter◦1 part per trillion◦1 ng/l Analogy –1 oz. in 7.5 billion gallons of water
Compound Common Name(s) Description
Results, ng/LC
WoodsD
JocelynE
Upland
FMeadow
s
TrimethoprimProloprimMonotrim
Triprim
Antibiotic—Used for urinary tract infections
50.2 63.5 33.0 <5
Antidepressants and Mood StabilizersBupropion Wellbutrin
Budeprion
Rx Drug—Antidepressant or smoking cess. aid
62.1 255.7 102.4 937.9
Lamotrigine LamictalRx Drug—Anticonvulsant and mood stabilizer
106.7 80.7 0.151 158.4
Venlafaxine Effexor
Rx Drug—Antidepressant; treats depression and anxiety
7,818 <0.001 59,087 3946
GemfibrozilLopidJezil
Gen-Fibro
Rx Drug—Treats high triglyceride and cholesterol levels
<0.005 <0.005 91,162 323
Compound Common Name(s) Description
Results, ng/LC
WoodsD
JocelynE
UplandF
MeadowsBeta Blockers
Atenolol TenorminRx Drug—Treats high blood pressure and angina (chest pain)
<5 <5 471.9 <5
Metoprolol LopressorToprol-xl
Rx Drug —Treats cardiovascular diseases, especially hypertension
<1 1728 1385 3752
PropranololCiplarInderalDeralin
Rx Drug—Treats hypertension, anxiety, and panic
<1 <1 23.8 <1
Pesticides
Atrazine AtazinaxWeedex ACommon Herbicide <2 94.5 <2 <2
Diuron (DCMU)
Di-onKarmex Common Herbicide 408.2 <5 <5 <5
Fluridone SonarAlligare Herbicide <5 93.9 <5 <5
CompoundCommo
n Name(s)
DescriptionResults, ng/L
CWoods
DJocely
n
EUpland
FMeado
ws
Caffeine Stimulant 1363.1 347.5 247.6 448.3
CotinineStimulant—Alkaloid found in tobacco and derived from nicotine
2.44 0.25 1.28 1.73
Sucralose Splenda Food Additive— artificial sweetener 122.4 96.6 29.2 258.7
Acetaminophen Tylenol OTC Drug—Pain reliever and a fever reducer 581.7 23.7 28.7 714.3
DEETChemical—Most common active ingredient in insect repellents
74.8 29.1 12.5 26.0
DiphenhydramineBenadrylUnisomNyQuil
OTC Drug—Antihistamine; treats allergies and cold/flu symptoms
2022 1258 1078 1260
Additional recommendation
◦ Some of the existing systems are not up to basic standards◦ Effluent screens and alarms should be added◦ New systems or those being upgraded should
time dosing and incorporate secondary treatment prior to soil treatment to mediate:◦ flow,◦ waste strength, and ◦ CECs
CASE STUDYMINNESOTA DEPARTMENT OF TRANSPORTATION (MNDOT)
REST STOP EVALUATION
Research background
◦ MnDOT owns and operates 52 septic systems serving the rest stops, truck garages and scales across Minnesota
◦ Little information exists or has been evaluated regarding ◦ Flows◦ Waste strength◦ Chemical usage
◦ Many systems are 30+ years old◦ Majority only have pretreatment in a septic tank◦ Difficult site conditions
◦ Compaction, fill soils, setbacks, etc
Field data gathered - facility
◦ Toilets, gallons per flush◦ Sinks, manual or automatic◦ Water conditioning devices, discharge location◦ Water treatment◦ Water foundations◦ Chemicals outside of 3M supplied by central administration◦ Flows recorded daily by manager from flow meter
Field data gathered – septic system◦ Pumping frequency◦ Problems/issues◦ Tanks: Type, depth, capacity, sludge, scum, pH., dissolved
oxygen, temperature◦ Pump operation◦ From pretreatment unit
◦ Septic/pump tank◦ A few advanced treatment unit
◦ Aerobic treatment units◦ Advantex
◦ BOD, COD, TSS, nitrogen, phosphorous◦ Fecal coliform and chemicals at select sites
Field data gathered – septic system continued◦ Distribution method: gravity, siphon, pump◦ Confirm size of system◦ Measure amount of ponding◦ Vegetation issues◦ Soil
◦ Separation to limiting condition◦ Texture/structure - sizing
Field data outcomes
◦ Use information gathered along with additional information to◦ Prioritizing upgrades based on risk factors
◦ Systems surfacing◦ Systems not protecting groundwater◦ Higher flows increase risk/weight◦ Age◦ Effluent quality
◦ Provide design and management recommendations ◦ Provide improved design standards
Treatment Levels
Nitrogen Data
◦ 14 systems had nitrogen concentrations over 120 mg/L◦ 24 exceeded 60 mg/l ◦ 73% of the systems have elevated nitrogen levels
compared to typical domestic wastewater◦ Due to the preponderance of blackwater versus
graywater
Organically Overloaded?
◦Due to conservative designs:◦ six systems were undersized based on organic loading◦Nine of the 52 systems had septic tanks less than the current requirements ◦ 3 days of hydraulic retention time
Results - Vertical separation
Distance from bottom of media to limiting soil condition
16 systems with evidence of surfacing ~300% of required size based on hydraulics
Amount of Separation (ft) Number of Systems>3 111-3 12<1 29
Maintenance
◦Thirty-three of the systems either had: ◦ no pumping data on last pumping ◦were in need of maintenance at the time of our assessment
◦For the systems with no data the interval had been greater than three years which is the minimum time frame allowed by MN Rules even for small residential systems
More In-Depth Research Underway
◦ 2 sites selected◦ Evaluating contaminant fate
and transport ◦ Groundwater mounding
MANAGING HIGH ORGANIC LOADS
Managing
◦ High organic loading will cause failure◦ Management considerations◦ Blackwater and graywater separation◦ Wastewater source separation◦ Advanced treatment◦ Holding tanks◦ Working with the owner
Wastewater Source Separation
◦May be economically beneficial to treat a waste stream separately or pump and haul it away ◦ Streams with very high chemical use that will
negatively affect the treatment system◦ Floor drains, utility sinks, laboratory drains,
disinfecting basins and dishwashers ◦ Streams that require a long detention time
Hold & Dose
◦Some chemical products must be contained in a separate tank and introduced into the system in small doses
Flow Equalization Tank & Haul
◦ Lower the extreme surge◦ Special events
◦ Too costly for infrastructure needed for special event extreme flow/strength◦ If the surge flows only
happen a few times a year◦ Pump the extra flow
from surge - equalization tank
Separation of Businesses
◦ Strip Mall ◦ Multiple stores◦ Different sources
◦ Initial tank for each facility◦Rental contract tied to wastewater quality & quantity
Treatment Options
◦Configuration of the system and the facility operation can be changed to influence treatment◦Start-up phase - monitor closely in first months of operation◦System is subject to the source◦ Educate users on proper procedures and how their usage is impacting the system
Fats, Oils, and Grease Management◦Best - Minimize their source◦ Use evaluation surveys◦ Find operations that can be changed or
eliminated – salad bar?
◦ Separate waste streams◦Grease interceptor or trap◦ Temperature moderation
Grease Trap
◦Grease traps are often first in the treatment train◦Baffles extend lower into tank than septic tank◦Needs frequent pumping◦ Sizing dependent on
pump truck capacity
Stereotyping◦Remember EVERY FACILITY IS UNIQUE; what works for one may not work for another◦What is a comparable facility?◦Heavily influenced by facility management◦Evaluate whether the facility is operating at assumed design values.
Recirculation◦ Recirculation of semi-treated effluent to dilute high strength
wastewater ◦ Denitrification◦ Example - Media filters
Aerobic Treatment
◦ Commercial units designed for high strength/commercial flows◦ Typically designed
in pounds of BOD removal per day◦ Fats, oils and
grease needs to be considered as well
Work with System Owners
◦Owner education is vital◦Most effective to demonstrate the economical benefits◦Management relates directly to waste stream
Work with System Owners
◦ Fix leaking plumbing fixtures◦ Lower water pressure◦ Use automatic shut-off faucets◦ Use water-saver dishwasher cycle
Work with System Owners
◦ Scrape plates into garbage, not the sink◦ Install drain covers and sink baskets/strainers◦Avoid use of a garbage disposal◦Avoid using slop sinks to dispose of liquid food items
Work with System Owners
◦Avoid use of harsh detergents: hand washing & automatic ◦Hand washing – disinfection process◦ Isolate harsh flows
STUDY REPORTS: SEPTIC.UMN.EDU